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This paper reports results of mathematical modeling applied to the stress and strain in epicentral zones before and after the large earthquakes that occurred on June 22, 2002 in the Qazvin Province, northwestern Iran (Mw = 6.4) and the Gujarat, India earthquake of January 26, 2001 (M = 6.9). The modeling relied on a method for calculating stress and strain in a blocky elastic isotropic heterogeneous medium disturbed by a set of faults that are due to an external tectonic stress field. The boundary conditions were specified based on geological and seismological data. It has been shown that the epicenters of large crustal earthquakes occur in zones of high stress concentration at the ends of tectonic faults. Rupture occurs when the relationship between acting tectonic stresses satisfies the requirement σyy/σxx >3, thus connecting zones of high stress. The evolution of the aftershock process is controlled by the stress drop caused by a new rupture, while the resulting aftershock clusters are in spatial correlation with the stress drop zone. The new rupture propagates in the direction of dominant tectonic fault orientation in the region. We show a relationship to exist between rupture length and the possible retrospectively predicted location and magnitude of the earthquake depending on the elastic energy buildup and its possible release under specified structural tectonic conditions. [ABSTRACT FROM AUTHOR]

This paper is the first in a series of studies generalizing the Map of Expected Earthquakes (MEE) medium-term earthquake forecast method and analyzing the prospects for its further improvement. Over the past 35 years, the MEE method has been used in seismically active regions around the world with different tectonic conditions and seismic regimes. The average prognostic efficiency of the algorithm was shown to be 2.5 times higher than for random guessing. The MEE can be further improved and upgraded. The new methods of data processing to be implemented into the upgraded MEE will significantly increase the amount of analyzed data, take into account the specific signs of the seismic process at different depths, use lineament–domain–focal (LDF) models of the structure of seismically active zones as stationary prognostic criteria, and build three-dimensional distributions of the probability of strong earthquakes. The improvement will involve an expansion of the list of used seismological precursors that have a physically justified link with the earthquake preparation process and the development of formalized techniques for identifying these precursors in the prognostic practice. [ABSTRACT FROM AUTHOR]

A destructive earthquake, especially if it occurs in areas of high seismic risk, in the form of certain factors, has a significant impact on the environment, including biodiversity. These factors (earthquake effects) are determined by the strength of the earthquake (manifestations of intensity on the earth's surface), local conditions (geomorphological, geological structure, level of urbanization and seismic risk, etc.), disaster-zone recovery processes (fast and effective recovery, localization and prevention of secondary consequences, environmental protection, state opportunities and political decisions, etc.). It is clear that these three important basic conditions of effects are different in different seismic regions and countries, which means that the impact of an earthquake on the environment is different. To consider the features and factors of the impact of an earthquake on the environment, the 1988 Spitak earthquake—one of the most detailed and comprehensively studied earthquakes in the world—was taken as a test object. The main purpose of this article is to highlight in more detail and more fully the possible natural and human factors of the impact of a strong earthquake on the environment and predict the extent of these impacts. Thirty-six major earthquake factors affecting the environment have been identified, which are conditionally divided into three main groups according to the time of formation and genesis: (a) purely seismic, (b) secondary seismic, and (c) post seismic. The paper also attempts to assess possible changes in these factors depending on global warming and a decrease in precipitation. [ABSTRACT FROM AUTHOR]

This paper presents the results of a detailed study of two relatively strong seismic events, occurred on November, 22, 2016 (МW = 5.0) and April 3, 2017 (МW = 4.8) at the northeastern flank of the Baikal rift zone in the areas of the South Muya and Kalar ranges. Both the events were followed by weak aftershocks (N = 178–539, Кр ≤ 11.0), whose epicenters were densely distributed over an area. The seismic moment tensors and hypocentral depths of the mainshocks were calculated from surface wave amplitude spectra. It has been shown that their sources were formed under the influence of the subhorizontal SE–NW extension and the subhorizontal or inclined NE–SW compression. Both the earthquakes were followed by noticeable macroseismic effects at epicentral distances up to 500 km. In the area of the Baikal−Amur Railway, their shaking intensity was IV–V MSK-64. The results obtained can be used in continuous seismic monitoring at the northeastern flank of the Baikal rift zone and can contribute to an objective seismic hazard assessment of the study area. [ABSTRACT FROM AUTHOR]

For the first time, a numerical comparison of the General Seismic Zoning (GSZ) maps with the effect of earthquakes that actually occurred after the publication of the maps was carried out. The area of zones of expected intensity on the GSZ map is compared with the area of isoseists from actual earthquakes. It turned out that the isoseist area is on average by an order less than expected according to the GSZ. This paper describes possible reasons for such an overestimation and proposes ways to improve seismic hazard assessments. [ABSTRACT FROM AUTHOR]

Abstract—In this paper, we explore the findings of monitoring the components of the Earth's natural electromagnetic (EM) field obtained in 2020–2021, as well as their link with rather strong seismic events within Baikal Rift Zone (in particular, the Kudarin earthquake (Dec. 9, 2020, Mw = 5.5)). During the observations of the magnetotelluric field more than one month prior to the seismic event, the increased conductivity of the tensor-sensitive parts of the sounded soil was recorded due to the displaced release of conducting fluid to the weak crust zones before the earthquake. 24 hours before the seismic event, the anomalous behavior of the electrical field vertical component (Ez) was observed as U-shaped oscillations every 5-30 s due to the electrical charge excitation and relaxation from the compression of quartz-containing rock. The first approximation showed that the analysis of magnetotelluric (MT) monitoring data could help identify medium- and short-term precursors of seismic events. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the identification of potential seismic damage in an area called Tanah Patah, Bengkulu City, Indonesia. This study is initiated by conducting site investigation and geophysical measurements. Ground motion prediction is conducted to estimate peak ground acceleration which is then used to estimate the damage intensity level during a large earthquake. A spectral matching method to generate ground motion at investigated sites is conducted. Seismic ground response analysis to observe ground response and soil behaviour is performed. The results show that peak ground acceleration in the study area is about 0.255–0.342 g during a large earthquake. IX is this area's Modified Mercalli Intensity (MMI) level scale. Since sandy soils dominate the study area, several sites could be more vulnerable to undergoing liquefaction. The thickness of potentially liquefiable soils is about 8.6–12.8 m. The results could help local governments develop spatial plans in the study area. [ABSTRACT FROM AUTHOR]

The paper presents the results of modeling the stress–strain state of the epicentral zone of the strong crustal Hanshin–Awaji earthquake, which occurred in the area of Kobe (Japan) on January 17, 1995, with a magnitude M of 6.9. In this work the author's method for modelling and analyzing the stress–strain state of the epicentral zones of crustal earthquakes was used. The geological, tectonic, and seismological data for the earthquake region are used as input data and boundary conditions for modeling. In this work it is shown that the main rupture arising at the origin of the earthquake is generated in a zone of high stress intensity at a certain ratio of the main tectonic stresses and propagates through areas of anomalously high stress concentration, causing maximum displacements in these zones. The results provide new insights into the focal mechanism of an earthquake, aimed at predicting the location and magnitude of strong crustal earthquakes in earthquake-prone areas. [ABSTRACT FROM AUTHOR]

This paper presents the results of analysis of the spatial distribution of repeated shocks. Data from the world earthquake catalog of USGS/NEIC from 1973 to 2014 were used. Short time intervals, no more than 10 hours after the main shock, and distances from the epicenter of the main shock, no more than 5°, were considered. The dependence of the number of repeated shocks on the distance from the epicenter was studied. Two properties of the spatial distribution of repeated shocks have been identified. The first property is that the curve describing spatial distribution has its maximum at a certain distance (approximately from 10 to 120 km) from the epicenter of the main shock. The logarithm of this distance is directly proportional to the magnitude of the main shock. The second property is that the position of the maximum does not depend on time, i.e., it is a stable spatial characteristic of the earthquake source. Based on these properties, a new way to determine the size of the rupture zone was proposed. [ABSTRACT FROM AUTHOR]

Abstract—: This paper reports the results of numerical modeling of the stress-strain state of the epicentral area before and after the August 24, 2014 earthquake in Napa, California, USA, compared to calculated data obtained in instrumental studies in the dilatation areas based on GPS observation results. Numerical modeling has made it possible to calculate the stress-strain state of the epicentral area affected by the tectonic fault system. GPS observation data on the epicentral area of the earthquake and the results of numerical modeling of the stress-strain state before and after the considered earthquake have been analyzed. A trend toward localization of earthquake epicenters in the region of high stress intensity concentration has been confirmed. It has been proved that aftershock development is due to the drop in stress caused by a new fracture and that the aftershock cluster that occurred was localized in the area of decreased stress intensity. [ABSTRACT FROM AUTHOR]

On 30 September 2009 at 05:16 pm local time (10:16 am UTC), a major earthquake registering a magnitude M 7.6 occurred off the coast of Padang in West Sumatra. This paper presents the observations from a reconnaissance mission that investigated the performance of structures, infrastructure and geotechnical structures within the affected region. As well as presenting the detailed observations made on the mission, insights as to why structures failed and deficiencies in the construction practices of the region are also presented. Considering the high seismic risk of this area and that seismic gaps suggest another earthquake with a magnitude greater than 8.7 may occur, these observations are particularly significant. One of the vital features of this earthquake was a number of very large and devastating landslides that occurred in the district of Pariaman. These landslides were not only extensive, but had an extremely high lethality. Another key feature of the earthquake was the surprisingly high number of government buildings that collapsed. The paper concludes by presenting a number of recommendations for both the rebuilding of failed structures as well as for hazard assessments of existing structures and geotechnical features. [ABSTRACT FROM AUTHOR]

In this paper, the parameters including maximum regional magnitude ( M), β-value, mean seismicity rate ( λ) and mean recurrence time were calculated for the Zagros belt. The mapping of parameters shows that there are several seismogenic zones in the Zagros with different seismic activity patterns. The results of calculation of the parameters for each seismogenic regions show that the parameters such as β-value, mean activity rate, annual probability and mean return period of events have been decreased from NW Zagros to SE with exception of Qatar-Kazerun transverse fault zone. This pattern is consistent with the increasing convergent rate from 4.5 ± 2 mm/year in the northwestern to 9 ± 2 mm/year in the southeastern part of the Zagros range (Vernant et al. in Geophys J Int 157:381-398, ). The anomalous values of seismic parameters are observed for the two transverse lineaments of the Zagros, Qatar-Kazerun fault zone and Zagros-Makran transition zone. These zones are characterized by high seismicity rate, low β-value and mean return period of earthquakes. The highest value of M coupled with very low seismic activity rate is observed for the MRF. It seems, in this zone, seismic energy is being released by a few relatively large earthquakes with longer return period. The other regions in the Zagros are characterized by high β-value, low seismicity rates and long recurrence time. The differences in the seismicity parameters are due to differing stress regimes and geological or structural heterogeneity of various parts of the Zagros belt . [ABSTRACT FROM AUTHOR]

Izmir, the third largest city and one of the major economic centers in Turkey, has more than three million residents and one-half million buildings. The city, located in a seismically active region in western Anatolia, was a subject of the 1997 RADIUS (Risk Assessment Tools for Diagnosis of Urban Areas against Seismic Disaster) project. In this paper, the seismic hazard of Izmir is investigated through probabilistic seismic hazard assessment. First, the seismic setting of Izmir is presented. Considering the statistics of earthquakes that took place in the region during the period 1900-2005, a simple seismic hazard model is used to facilitate the assessment. To account for modeling uncertainties associated with the values of seismicity parameters, a logic tree procedure is employed in carrying out the seismic hazard computations. The resulting weighted average seismic hazard, presented in terms of peak ground acceleration and associated probability of exceedence, could be considered the 'best estimate' of seismic hazard for Izmir. Accordingly, for a return period of 475 years, for rock sites, a PGA value of 0.34 g is calculated. This PGA hazard estimate is close to the current code-recommended design acceleration level for Izmir. [ABSTRACT FROM AUTHOR]

Vulnerability assessment of an urban area to earthquake hazards is the requirement to attaining sustainable urban resilience. Quetta city is the capital of the province of Balochistan surrounded by mountains with the existence of many active faults. The main objective of the current study was to assess the earthquake vulnerability in Quetta valley. A total of 400 households were selected for the primary household survey. A simple random sampling technique is employed using proportionate allocation method because of the heterogeneity of the area in terms of population. Secondary data was taken from the Geological Survey of Pakistan (GSP), the Pakistan Bureau of Statistics (PBS), and the United States Geological Survey (USGS). Analytical Hierarchal Process (AHP) & Weighted Linear Combination (WLC) methods are used to identify earthquake vulnerability. The results of the study reveal that the Northwestern and Southeastern parts of Quetta are seismically vulnerable to earthquake hazard; its geology coupled with the human dimension indicates a more disastrous future events. Results of the composite earthquake vulnerability show that seven out of thirteen Zones of Quetta city are highly vulnerable to all four components of vulnerability. Four Zones have a medium level of vulnerability and only two Zones are considered low earthquake vulnerable Zones in the study area. The topmost influential factors that make Quetta city highly earthquake-vulnerable are the soil type (0.45), peak ground acceleration (0.34), proximity to the hospitals and fire service stations (0.22, 0.21), elderly population (0.22) and fault lines (0.21) as shown in Fig. 12. This research study has significant implications for urban planners and provides a risk reduction platform in order to reduce future earthquake losses and make Quetta city more resilient and sustainable. [ABSTRACT FROM AUTHOR]

Detailed and accurate historical earthquake disaster data are an important basis for understanding the characteristics of earthquake disaster losses and for conducting research on earthquake disaster prevention strategies and post-earthquake emergency rescue work. Due to different project scopes and discrepancies in data accuracy, the currently available databases may contain errors such as missing data or data with low accuracies. In this study, we developed the Mainland China Composite Earthquake causing Casualties Database (MCCEC-DAT), which contains 252 historical earthquake records that span from 1966 to 2021. The database contains earthquake attribute information (earthquake time, location, epicenter latitude and longitude, focal depth, epicentral intensity, etc.), loss information (number of deaths and injuries, building damage ratio, economic loss, cause of death, etc.), and socioeconomic data (population, population density, area of each zone of seismic intensity, mortality rate, etc.). This database also contains the lethality levels generated by this study. These levels are the result of the quantitative evaluation of the overall characteristic levels of the earthquake area. Furthermore, this metric permits the direct comparison of different spatial locations. Based on the results of the statistical analysis, this work shows that the distribution of historical earthquakes in mainland China has obvious spatial and temporal characteristics. Events are mainly distributed throughout the southwest region, and the magnitudes of those events are relatively diverse. The mortality rate is significantly correlated with the building damage ratio and the lethality level. The lethality level can not only facilitate an improved understanding of the comprehensive level of historical earthquake regions, but this metric also provides a quantitative foundation for the comparative analysis of earthquakes between different regions. Furthermore, the database can also provide a foundation for future research, such as research into assessing the loss from earthquake disasters. [ABSTRACT FROM AUTHOR]

Automated assessment of felt reports in accordance with the regionalized DYFI questionaries were implemented on mobile applications and messengers of the seismological service eqalert.ru. The new tool was tested on Sakhalin Island, which is considered as an active crustal region. We have developed a regression relationship between the peak ground acceleration and the community internet intensity for the studied area. The community internet intensity calculated from a large number of felt reports has a variance comparable to those given from a prediction equation of the physically based ground motion parameters. The given approach is considered as a state-of-art tool for the rapid collecting and assessment of macroseismic data. It may be used both with the weighted average method for generating high-quality shaking maps immediately following the felt earthquake. It is also a good way to involve the population in ground shaking measures. [ABSTRACT FROM AUTHOR]

Anomalies in the ionic and gas composition of groundwater before earthquakes (hydrogeochemical precursors, hereinafter HGCP) are considered according to data of systematic observations in ten self-flowing wells and springs in seismically active regions of Russia (Kamchatka Peninsula), Uzbekistan, Japan, and Iceland. Using an extended set of earthquake parameters, it was shown that HGCP were manifested for 1–9 months in the near and intermediate zones of the future earthquake sources with Mw = 5.3–7.8. Such properties of hydrogeochemical precursors allow their use for predicting the magnitude and time of expected seismic events, as well as their impact in the observation area. A model is presented for a registered precursor in the form of the ionic composition of groundwater in self-flowing well based on observational data on concentrations of anions and cations and on a mathematical model for the mixing of two waters of contrastingly different composition in a zone of increased conductivity. Calculations for one of the wells are presented as an illustrative example of the chemical composition of two mixing waters in the aquifer and in the wellbore. This model and observational data are used to estimate parameters of the disturbed state of the well–aquifer system during the preparation of an earthquake: the relaxation time of the water pressure pulses (t0) and the movement time of mixed water (τ0). The morphology and duration of HGCP are controlled by relations between t0 and τ0. The further development of HGCP studies and their application in predicting earthquakes require a technical modernization of the system of hydrogeochemical observations and the development of HGCP models for individual wells. [ABSTRACT FROM AUTHOR]

In this paper, significant variations in rate of moderate-large earthquake occurrence during the last two centuries at the north of Persia (Alborz, Azarbaijan, and Kopeh Dagh seismotectonic provinces) were chronically investigated. Depths of some historical and instrumental earthquakes were reasonably estimated using macroseismic data. Also, empirical relationships were developed between the maximum intensity and magnitude of the earthquakes in the north of Persia. Two centuries of earthquake data (M ≥5.0) reliably demonstrates that quite periods with durations of about a few years to two decades have happened and have been subsequently followed by active periods with durations of about 10 to 70 years. The time variation of seismic hazards (achieved by the macroseismic maximum intensity, I ≥IV) almost displays a similar behavior at the study area. According to both patterns of the time variations of seismicity and the seismic hazards, it may conclude that we are within a low rate of seismic period, and we may expect a higher rate of seismicity at the Alborz in the next decades. Finally, in both the Azarbaijan and Kopeh Dagh areas, we discovered considerable migrations of the seismicity from the east to the west. [ABSTRACT FROM AUTHOR]

A shallow-focus (3.8 km deep) and low-magnitude ( M 3.8) earthquake occurred near Sheikhupura on August 08, 2010. Shaking was felt in parts of Potwar and northern Punjab but no associated damage has been reported. Tectonically, this earthquake occurred to the south of the Salt Range in the Punjab Seismic Zone (PSZ), a shallow-focus, moderate-level seismic zone characterized by steeply dipping strike-slip and extensional faults. The focal mechanism solution, using the seismological data of the United States Geological Survey and local observatory, shows an EW-trending fault plane dipping 710 N similar to the normal faults reported in the area previously. On the basis of the imposition of the stress field on the northward-moving Indian plate and the nature of the FMS of the previous and this earthquake, the Sheikhupura earthquake is considered as one of the intraplate earthquakes occurring frequently in the PSZ. The location of the event on the Bouguer gravity maps coincides with the zone of high gravity anomaly reflecting igneous intrusion(s) or, more likely, structural disturbances (i.e., extensional faulting in the basement). [ABSTRACT FROM AUTHOR]

Surface topography (whether subaerial or submarine) is a product of plate tectonic, geological, climate and surface processes. Plate tectonic processes, predominantly operated through earthquake cycle, dominate, at least in the seismically active regions, and are responsible for a significant amount of topography build up. On a shorter time scale, they appear to cause devastation, but on a longer time scale, they lead to the development of diverse landscapes which not only makes them look beautiful but also inhabitable. The topography build-up, due to deformation caused by earthquake processes, depends upon the mechanism of deformation and earthquake occurrence. The earthquake occurrence mechanism is different in the plate boundary regions as compared to that in the plate interior regions. Here in this article, I discuss the nuances of crustal deformation in the interplate and intraplate regions in the context of India and India plate. [ABSTRACT FROM AUTHOR]

Crustal earthquake ruptures tend to initiate near fluid-rich zones. However, it is relatively unknown whether fluid-rich zones can further promote or arrest these ruptures. We image the electrical resistivity structure around the focal area of the 2016 Kumamoto earthquake sequence by using 200 sites broadband magnetotelluric data, and discuss its quantitative relationship to earthquake initiation, growth, and arrest processes. The ruptures that initiated along the outer edge of the low-resistivity fluid-rich zones (< 30 Ωm) tended to become large earthquakes, whereas those that initiated either distal to or within the fluid-rich zones did not. The ruptures were arrested by high-temperature (> 400 °C) fluid-rich zones, whereas shallower low-temperature (200–400 °C) fluid-rich zones either promoted or arrested the ruptures. These results suggest that the distribution of mid-crustal fluids contributes to the initiation, growth, and arrest of crustal earthquakes. The pre-failure pressure/temperature gradient (spatial difference) of the pore fluids may contribute to the rupture initiation, propagation, and arrest. [ABSTRACT FROM AUTHOR]

The evolution of scientific views on the structure of the sources of strong earthquakes at the end of the 20th and beginning of the 21th century in Russia is considered. The lack of a clear, consistent understanding of the structure of sources of the strongest seismic events was initially typical of the scientific concepts that emerged in the main developed countries. In the 1950s, at the Schmidt Institute of Physics of the Earth of the USSR Academy of Sciences, G.A. Gamburtsev formulated a hypothesis about the stability of the seismic regime of a system of seismic sutures over a long period of time (a few hundred years). The seismic sources of the recently studied earthquakes are located in the regions of large faults. With the increase in magnitude, they become more extended and structurally complex. In the considered cases, there are sources that are relatively simply to reconstruct, which encompass the fault planes of the large existing faults (Spitak source, M = 6.8), as well as sources that are more complex, formed in the disjunctive nodes, or those that encompass the crustal blocks. For example, the seismic source of the Altai earthquake (M = 7.3) is characterized by a volumetric structure and is developed along the boundaries of the large seismogenic blocks. The source of the Wenchuan earthquake (M = 7.9) is most complicated. It appears as a three-dimensional (3D) structure composed of a few crustal blocks framed by two extended northeast striking faults and separated by a transverse fault of the northwestern orientation. The sources having a different focal structure differently manifest themselves in the structure of seismic dislocations on the surface and in the distribution of aftershock hypocenters at depth. The anomalously low velocity "pockets" that were identified by the method of local seismic tomography in the source areas of the Spitak and Altai earthquakes and that accompany the main and secondary faults at depth are likely to be the zones of the dynamic influence of these faults. The damaged near-fault zones, with abundant cracks and fractures, are the severely destroyed inclusions in the crustal rocks, and they hamper the propagation of seismic waves. Therefore, within these pockets, the P-waves propagate at a lower velocity than the undamaged geological medium. The results of the paleoseismological study of seismic faults in the trenches showed that strong earthquakes also occurred in the same sources in the past, and the period of recurrence of the strongest seismic events ranges from a few hundred to the first thousand years. Thus, the integrated studies of the source zones of the strongest earthquakes that were conducted in the past decades in different regions of Eurasia have shown that the hypothesis of Gamburtsev has remained relevant. [ABSTRACT FROM AUTHOR]

China has suffered from severe earthquake disasters in recent years. In order to explore the impact of severe earthquakes on public risk perception on different time scales, four surveys were conducted twice each after the severe Wenchuan and Yushu earthquakes. t tests were performed between two consecutive surveys to explore the change of public risk attitudes. The results demonstrated that after the two severe earthquakes, the public seismic risk acceptance has increased over time, and the comparison between pre- and post-Yushu earthquake illustrated that the severe disaster had more impact on vulnerable population such as females, children and low-income people. Moreover, linear regression models were employed to find the determining factors of public acceptance towards earthquake risks. It was discovered that the public perceived earthquake effect had significant negative relationship with seismic risk acceptance, and public trust towards local government had positive relationship with the risk acceptance. This study could help government to gain better understanding of public mental status and take more effective disaster preparedness measures when preventing and responding to a severe earthquake. [ABSTRACT FROM AUTHOR]

Earthquakes usually occur after some preliminary anomalies in the physical and chemical characteristics of environment and earth interior. Construction of the models which can explain these anomalies, prompt scientists to monitor geophysical and geochemical characteristics in the seismic areas for earthquake prediction. A review of studies has been done so far, denoted that radon gas shows more sensitivity than other geo-gas as a precursor. Based on previous researches, radon is a short-term precursor of earthquake from time point of view. There are equal experimental equations about the relation between earthquake magnitude and its effective distance on radon concentration variations. In this work, an algorithm based on Dobrovolsky equation $$ (D = 10^{0.43M} ) $$ with defining the Expectation and Investigation circles for great Tehran has been used. Radon concentration was measured with RAD7 detector in the more than 40 springs. Concentration of radon in spring, spring discharge, water temperature and the closeness of spring location to active faults, have been considered as the significant factors to select the best spring for a radon continuous monitoring site implementation. According to these factors, thirteen springs have been selected as follow: Bayjan, Mahallat-Hotel, Avaj, Aala, Larijan, Delir, Lavij, Ramsar, Semnan, Lavieh, Legahi, Kooteh-Koomeh and Sarein. [ABSTRACT FROM AUTHOR]